The field of this disclosure relates to antimicrobial metal alloy compositions and especially to stainless steel alloys with antimicrobial properties
It is known that antimicrobial effects are shown by ions of mercury, silver, copper, iron, lead, zinc, bismuth, brass, gold, aluminum, and other metals. The technical paper; “Antibacterial Metals, a Viable Solution for Bacterial Attachment and Microbiologically Influenced Corrosion” by Kurissery et a provides an excellent overview of the importance of antimicrobial metals. Biofilm formation on surfaces is of concern to the public health. Also, biofilms are known to be deleterious to materials as they may induce corrosion. These reactions are referred to as biocorrosion or microbiologically influenced corrosion (MIC) when the underlying substratum is a metal or metal alloy. MIC is a serious problem in a number of industries including power generation, petrochemical, pulp and paper, gas transmission and shipbuilding. Conservative estimates place the direct cost of MIC at $30 to $50 billion per year at this time. The magnitude of the problem calls-for wider attention and collaboration between established research groups and laboratories that specialize in aspects of metal-microbe interactions. Such groups may focus on microbiology, metallurgy, civil & environmental engineering and biotechnology.
Stainless steel is widely used for architectural and decorative applications such as hand rails, faucets and other objects that receive continuous human contact. Stainless steel surfaces have no known antimicrobial effect. In the prior art we find that a small amount of copper is known to have been included as a constituent of stainless steel to achieve antimicrobial effects, but this approach is relatively expensive due to the cost of copper and the extra steps required in processing. Another problem is that such alloys exhibit lower corrosion resistance. Silver has also been used in stainless steel alloys but suffers the same issues as copper. Antimicrobial features in stainless steels have been shown to be effective against: Escherichia coli, Candida Albicans, HIV, and others microbes and viruses.
Antimicrobial coatings are known in the art as exemplified by U.S. Pat. No. 6,929,705 to Myers et al wherein a liquid dispersion containing metal component-supporting oxides and zeolite powders is applied to metal parts. Laminations such as taught in U.S. Pat. No. 7,521,489 to Shimazaki have been used wherein an antibacterial metal such as silver is used with layers of structural metals such as steel.